In case you haven’t seen this photo, all ll I can say is … AMAZING. Austrian astrophotographer Gerald Rhemann photographed Comet Lovejoy on Dec. 13 with a tail at least 20 degrees long. That’s more than 40 full moons side by side! The tiny version of the photo I’ve posted only hints at the incredible structures in the comet’s blue gas tail. Click the image to see the monster version. See what I mean?
The kinks, twists and blobs tell the tale of a tail flayed and hammered by the solar wind. Gases like carbon monoxide released from the comet’s nucleus as it vaporizes in sunlight are ionized (electrified) by the sun’s ultraviolet light and form the blue-tinted ion tail. Changing magnetic fields embedded in the sun’s solar wind stream by and interact with the ionized gases, sculpting bizarre shapes and multiple streamers. Like a wind sock, gas tales belie the wind’s strength, speed and direction.
Toward the top of the photo and roughly parallel to the gas tail look for the smooth, pale yellow dust tail. Dust from the comet, released along with the gas, gets pushed back behind the comet’s head by the pressure of sunlight to form a separate tail defining the comet’s curved orbit.
Since dust is neutral, the solar wind doesn’t mess with it like the ionized (electrified) gases in the ion tail.
Lovejoy’s tail will likely grow even longer as the comet heads toward perihelion (closest approach to the sun) on December 23 and solar heating intensifies.
Unfortunately, the comet has been slowly moving away from Earth and slowly fading since late November.
At the moment, Lovejoy’s making its way across the constellation Hercules and best viewed in the morning sky just before the start of dawn when it stands some 30 degrees above the eastern horizon. For observers in mid-northern latitudes, Hercules is also visible very low in the evening sky with the comet just 10 degrees high and dropping lower by the night.
Although compromised by moonlight, it’s still visible in binoculars and small telescopes glowing around magnitude 6. In about a week, the moon will be a crescent and much less of a bother. The tail will be much more obvious at that time.